Furnace door



A 99 99, 1995. G A REHM 1,999,792

FURNACE DOOR Filed Feb. 1, 1-932 INVENTOR GUSTAV A REHM Patented Apr. 30, 1935 UNITED, srA'res Lara FURNACE DOOR Gustav'A. Rehm, Worcester, Mass, assignor, by

mesne assignments, to

tion, Worcester, chusetts Riley Stoker Corpora- Mass., a corporation of Massa- Application February 1,1932, Serial No. 590,186

7 Claims.

This invention relates to furnace doors, and more particularly to a door adapted to be mounted on the wall of a combustion furnace and arranged to permit inspection of the furnace interior. 7

It is necessary for a furnace operator to know what is actually taking place inside the furnace chamber, so that he may be able to make any adjustments required to improve combustion efli 'ciency. Wall, a great volume of air will rush into the furnace and disturb combustion conditions to such an extent as to render inspection valueless. Furthermore, the glaring light and the intense radiant heattransmitted through the large opening are extremely uncomfortable to the operator and greatly hinder his work. An accurate in-' spection of the fuel bed, combustion flame, or furnace linings is impossible under these conditions. 7

It has heretofore been proposed to overcome these difficulties by providing a small inspection door'having a colored glass therein, through which the operator may view the furnace interior. Such prior constructions have not proven entirely satisfactory, since it is found that the glass is subject to frequent breakage, either from the heat or v from accidental blows. Furthermore, the doors of the prior art have been expensive to manufacture and awkward and inconvenient to use.

It isaccordingly the main object'of the invention to provide a simple and inexpensive furnace door which will assist the operator in obtaining an accurate knowledge of the combustion conditions within the furnace, and which will protect the operator from the excessive heat and glare of the combustion flame.

It is a further object of the invention to provide a furnace inspection door which will have a longlife of useful service and be freefrom breakage difficulties. 1

It isa further object to provide a simple construction for a furnace door which can be conveniently used for inspection, for taking of furnace temperatures, or for the insertion of a slice baror steam lance if occasion demands. I

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in' which like reference numerals indicate like parts,

If a large door is opened-in the furnace as a circular disk slightly larger in diameter Fig. 1 is an elevation of a furnace door in closed position;

Fig.2 is an elevation of the door inspection of the furnace interior;

Fig. 3 is an elevation of the door in position to 1 5 permit the taking of furnace temperature, as by means of an optical pyrometer; V

Fig. 4 is anelevation of the doorin position for insertion of a slice bar or steam lance; and

Fig. 5 is a section on the line 55 of Fig. 1.

The embodiment illustrated comprises a door frame It shown as a flat square plate provided in position for with a slightly raised boss H at each corner.

Each boss has an opening i2 therethrough so that the plate may be readily bolted against the outside of a furnace wall. In the center of the door frame I have shown a circular opening it, which it will be understood will, register'at installation with an opening in the furnace wall; This opening it is preferably'surrounded on the furnace side by an annular projection or flange I 5 .(Fig. 5), which fits into the opening in the refractory material of the wall. While Ifd'o not wish to be limited to any particular sizes for the various parts, I have found thata diameter of four inches for the opening it is satisfactory in actual practice.

The opening I4 is normally closed by means of a manually operable door or shutter l 6, shown than the opening. The disk i6 is, provided with a radially projecting lug or car It which isfpive.

, otally connected to the door frame by means .of

a rod l9. This rod extends horizontally through I both thelug l8 and a boss located on the outer face of the plate and above the opening M. The rod I9 is rigidly fastened to the lug l8, pref-, erably by means of a transverse pin 22 extending through these parts, and a nut 23 (Fig. 5) is screw threadedtothe inner end of the rod to .4 hold it in place without preventing rotation thereof. Therear faceof the plate it maybe recessed at 24 to receivethis nut, so that the furnace wall need not be cut away at installation.

7 The plate H! is provided with an annular flange 26 surrounding the opening M and flush with the boss 2E3, andwhen the shutter 56 is in its closed position the rear face thereof contacts with this flange.

In order tolprevent overheating of the door I6, I provide means for passing a slight amount of cool-air adjacent to the surface thereof. For this purpose I have shown shallow radial grooves 21 in the face of the flange 26, through which grooves small streams of air from the atmosphere 5 furnace chamber.

flow into the opening M and thence into the furnace under the influence of the furnace draft.

The door It may be manually operated by means of a handle 28, which is preferably formed by bending the outer portion of the rod is at right angles and in line with the center of the door. By thus forming the handle 28 integral with the pivot rod Hi, the construction is considerably simplified. Stops 36 may be provided on the flange 26 at one side of the door opening hi to limit the movement of the door in one direction. These stops preferably project from the flange a distance equal to the thickness of the The door movement maybe limited in door. the opposite direction by the -pin 22 which cooperates with a lug 3 i on the door frame. In the illustrated embodiment, the door is free to swing through an arc of i8?! degrees, from the position shown in Fig. 1 to the position shown in Fig. 3.

In order to protect the operator from the brilliant glare of the furnace and permit a more accurate observation of combustion conditions, 'I

provide a plate. 32 of a suitable semi-transparent material, 'such as colored glass, which'is'positioned in front of the opening i i. This plate is preferably shaped as a circle slightly larger'in diameter than the opening M and may be supported in a ring 33'of asbestos (Fig. 5) located in a recess in an annular frame 34. A flat annular plate 36 is fastened'against the outside of the frame by means'of screws 31, and serves'to holdthe glass'32 in place. Theannuiar frame St is pivotal-1y supported from the rod 69 by means of a. radially projecting. ear or lug 38. A pin 3% extends transversely through the rod i@ just outside the lug 38, and holds the frame 3:3 closely adjacent. to the outer'surface of the'door it. A tongue. 4| projects radially from the frame 3 opposite to the lug 38, and this tongue fits the upwardly open slot in a hook-shaped projection 42formed'integral with the annular flange 25. below the opening M. This construction locks theframe 34 in place against any internal pres sure which may accidentally. develop within the The lug 3! preferably projects a little above the face of the stops 3E, and thus serves as an abutment to limit the move ment of the frame 34.

It will 'now be apparent that when the door'it a isswungyto the open position shown inFigfl' 2,

the operator may observe the furnace interior through the glass 32. Moreover, this movement of the 'door'allows an increased volume of airito flowinto the furnaceibetween the frame 35 and the flange 26 through the space normally occupied by the door, thus cooling'the glass during the observation period. Still further protection.

for the glass is obtained by providing a coarse wire mesh screen on the furnace. side thereof This. screen is supported by the. annular frame Stand" maybe integrally joined'thereto during I the; operation of casting the frame; The screen 44 intercepts a considerable part of the radiant heat which would otherwise reach theglass.

In case it is desired to measure. the furnace temperature by means of an optical. pyrometer, it is necessary to swing the glass 32 away from the opening Mi. For this purpose I provide a lost-motion connection between the handle 28' The preferred construction integral'with" the frame 3. 5 and arranged to cooperate with the pin. 48. When the handle'is swung upwardlyto, the positionshown in Fig. 2

the-pin l'flwill strike the lug $5, andifithe' handle the parts will return by gravity to the closed position shown in Fig. 1. In the event that the operator wishes to use both hands on a slice bar or steam lance, he may swing the frame 36 to a position directly above the opening M, as shown in Fig. 4. The parts willthen :retainth-isuposition until-the.= operator completes his work. and closes the door by swinging the handle 28 downwardly.

It will now be clear that when the door is fully closed, as shown in Figs. 1 and 5, the glass 32 is shielded from radiant heat by the shutter I6, and the'la-tter is cooled by the small streams of air flowing through the grooves 21. The glass is furthermore protected against accidental breakage from the outside by the handle 28, which extends across its face. When the operator wishes to. view the furnace interior he grasps the handle 28 and swings the-shutter. l6 laterally and upwardly 'to th position shown in Fig 2.- The glass is then cooled by the increased air flow; betweenthe flange 26 and the frame 34, and is If a gas partially shielded by the screen A i. explosion occurs in the furnace while the operator is making an observation, his, face is thoroughly protected,'since any outward blast will bedirected-v laterally. A further movement of the handle will swing the glass clear of the opening for direct l The construction is comparatively simple and inexpensive to manufacture and there is nothing which is likely to cause trouble in actual operation. The glass is protected fromheat and accidental breakage, and the entire apparatus. is;

welladapted to' the purposes for which it}isintended.

Having thus described "my invention-what I claim as new" and desire to secure by Letters Patent is: i

1. A furnacedoor assembly comprising a frame havingan opening therein, a plate of semi-transparent material in front of the opening,-a shuttersupported between the'plate andthe frame to shield the plate from radiant heat, the shutter. and frame being so shaped and arranged asto provide passages therebetween which direct air across the furnace side of the shutter and thence through the opening, and means tomove the shutter away from the shielding position to permitan. observation of the furnace interior through the opening. 1

2. A furnace door assembly comprising a-framehaving an opening therein, a plate of semi-transparent material in front of the opening, a shutter supported on the furnace sideof the plate to shield the plate from radiant heat, both the-plate and shutter being movable to expose the open-- ing,. a handle to operate the shutter, and alost motion connection between the shutter and the plate, whereby a predetermined movement of' the handle: will move the shutter from behind" the plate without movingthe'plate, and a further movement of the-handlewill move the plate from in front of the opening. v

3. A furnace door assembly comprising a. frame having an opening therein, a rod rotatably mount ed in the frame abovethe opening, ashutter rigidly connected to the rod and. normally closing the opening, a plate of semi-transparent ma- 7 terial mounted outside of the shutter, and a handle connected to the rod and extending across the outer face of the plate, the handle serving to protect the plate from'breakage and to aid in swinging the shutter from behind the plate when it is desired to observe the interior of the furnace.

4. A furnace door assembly comprising a frame having an opening therein, a rod rotatably mounted in the frame above the opening, a shutter rigidly connected to the rod and normally closing the opening, an annular frame located outside of the shutter. and pivotally supported from the rod, a plate of semi-transparent material mounted in the annular frame, meansproviding a lost motion connection between the rod and the annular frame, and a handle connected to the rod, Said parts being so constructed and arranged that turning the red by means of the handle will first swing the shutter from in front of the opening and then swing the annular frame from in front of the opening.

5. A furnace door assembly comprising a frame having an opening therein, a rod rotatably mounted in the frame above the cpening; a shutter rigidly connected to the rod and normally closing the opening, an annular frame located outside of the shutter and pivotally supported from the rod, a plate of semi-transparent material mounted in the annular frame, means providing a lost motion connection between the rod and the annular frame, a handle connected to the rod, a tongue projecting from the annular frame, and a hook shaped projection on the first mentioned frame below the opening, said projection normally overlying the tongue and thus supporting the plate and annular frame against any pressure which may develop in the furnace.

6. A furnace door assembly comprising a frame having an opening therein, a rod rotatably mounted in the frame above the opening, a shutter rigidly connected to the rod and normally closing the opening, an annular frame located outside of the shutter and pivotally supported from the rod, a plate of semi-transparent material mounted in the annular frame, and means providing a lost motion connection between the rod and the annular frame, the outer portion of the rod being bent to form a handle extending across the plate when the shutter is in closed position.

7. A furnace door assembly comprising a frame having an opening therein, a plate of semitrans parent material in front of the opening and spaced from the frame to provide a passage leading to the opening, and a shutter supported between the frame and the plate in such a position as to prevent excessive air fiow through the passage and to shield the the shutter being movable away from the shielding position to permit an observation of the furnace interior through the opening and to allow a large volume of air to flow through the passage in contact with the rear surface of the plate and thence to the opening.

GUSTAV A; REHM.

plate from radiant heat, 

